6 July 2015

Contents

1. Time-of-day clock stopped; invalid configuration information
2. Diskette drive 0 seek failure
3. Diskette drive 0 seek failure, part 2
4. System locks up when selecting 8 MHz clock speed
5. Self test does not detect correct memory configuration after upgrade

Problem Log

Time-of-day clock stopped; invalid configuration information

After performing the power-on memory test, the system reports

640K Base Memory, 00000K Extended
Time-of-day clock stopped
Invalid configuration information - please run SETUP program

The battery has failed. Replace it; part is 3.6v NiMH (Varta 3/60DK). Equivalent batteries available in 3-pin or 2-pin through-hole packaging; mainboard provides mounting for either.

Diskette drive 0 seek failure

When performing the floppy disk drive self-test, the drive is selected (the activity lamp lights) but the heads do not step and the spindle motor does not turn. The system reports

φû▂δ@╟♀FDiskette drive 0 seek failure
 Strike the F1 key to continue

If the onboard FDC is made secondary (J10) and a primary FDC is installed into an ISA slot, no error is reported and all floppy disk drive functions are available as normal.

U77 (74LS00) has failed. Replace it.

Diskette drive 0 seek failure, part 2

After replacing U77, the spindle motor turns when the drive is selected, but the seek test still fails with the same garbled error message from above.

The 8 MHz system clock is missing due to a corroded via between pin 4 of U114 and pin 9 of U97. This clock is required for correct operation of the intel P8272A FDC, even when the CPU clock is set to some other frequency. Repair the trace.

System locks up when selecting 8 MHz clock speed

If the system is switched to 8 MHz operation, the system locks up immediately, requiring a hard reset. The front panel display changes to indicate the 8 MHz clock has been selected, but the corresponding tone is not heard from the speaker.

The 8 MHz system clock is missing. See Diskette drive 0 seek failure, part 2, above. When the trace is repaired, the 8 MHz clock speed becomes selectable as normal.

Self test does not detect correct memory configuration after upgrade

When upgrading from 640 KB memory to 1024 KB, the system continues to test only 640 KB memory. If the memory configuration information is updated using the D2SETUP program, the system still tests 640 KB and complains that the memory configuration is invalid.

The mainboard memory configuration is controlled by two jumpers, J1 (RS1) and J2 (RS2). These are located along the rear edge of the mainboard, between the ISA slots.

† With 1 MB installed on the mainboard, the memory is arranged as 512 KB conventional + 512 KB extended.